libc/test/src/sys/random/linux/getrandom_test.cpp

   1 //===-- Unittests for getrandom -------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "src/__support/CPP/array.h"
  10 #include "src/errno/libc_errno.h"
  11 #include "src/math/fabs.h"
  12 #include "src/sys/random/getrandom.h"
  13 #include "test/UnitTest/ErrnoSetterMatcher.h"
  14 #include "test/UnitTest/Test.h"
  15
  16 TEST(LlvmLibcGetRandomTest, InvalidFlag) {
  17   LIBC_NAMESPACE::cpp::array<char, 10> buffer;
  18   LIBC_NAMESPACE::libc_errno = 0;
  19   ASSERT_THAT(LIBC_NAMESPACE::getrandom(buffer.data(), buffer.size(), -1),
  20               LIBC_NAMESPACE::testing::ErrnoSetterMatcher::Fails(EINVAL));
  21 }
  22
  23 TEST(LlvmLibcGetRandomTest, InvalidBuffer) {
  24   LIBC_NAMESPACE::libc_errno = 0;
  25   ASSERT_THAT(LIBC_NAMESPACE::getrandom(nullptr, 65536, 0),
  26               LIBC_NAMESPACE::testing::ErrnoSetterMatcher::Fails(EFAULT));
  27 }
  28
  29 TEST(LlvmLibcGetRandomTest, ReturnsSize) {
  30   LIBC_NAMESPACE::cpp::array<char, 10> buffer;
  31   for (size_t i = 0; i < buffer.size(); ++i) {
  32     // Without GRND_RANDOM set this should never fail.
  33     ASSERT_EQ(LIBC_NAMESPACE::getrandom(buffer.data(), i, 0),
  34               static_cast<ssize_t>(i));
  35   }
  36 }
  37
  38 TEST(LlvmLibcGetRandomTest, CheckValue) {
  39   // Probability of picking one particular value amongst 256 possibilities a
  40   // hundred times in a row is (1/256)^100 = 1.49969681e-241.
  41   LIBC_NAMESPACE::cpp::array<char, 100> buffer;
  42
  43   for (char &c : buffer)
  44     c = 0;
  45
  46   LIBC_NAMESPACE::getrandom(buffer.data(), buffer.size(), 0);
  47
  48   bool all_zeros = true;
  49   for (char c : buffer)
  50     if (c != 0)
  51       all_zeros = false;
  52
  53   ASSERT_FALSE(all_zeros);
  54 }